Which spec is best value between these 2 please?

HI everyone,

IM looking at purchasing a MBP over the weekend,and would appreciate some opinions into which of the 2 specs below would be the best value?

Basically,I've been given a budget of £1600 to spend and have been considering the following:

Entry level 15" with 2.2GHz quad core i7,16GB RAM and 256GB flash storage (£1599)

13" Retina display 2015 model with 2.9 GHz dual core i5, 16GB RAM and 512GB flash storage (£1559)

Either size screen is fine for my current needs,so I'm not really letting that part bother me too much.

Many thanks for any help in advance.